Whether about seeing the dot specifically or not, yes, major-league hitters have to be able to see the rotation of the ball as it leaves the pitcher’s hand, so they can predict the break of the pitch. They also account for things like arm angle, arm speed, and so on. Of course, for many players, this is probably an instinctive ability… they may not be consciously processing “Oh, the ball is rotating like so, therefore it must be a sinker.” It may be more instinctive than that for many players.